Limbal Stem Cell Transplantation Research Articles

Curative effect of pterygium resection and autologous limbal stem cell transplantation combined with amniotic membrane transplantation in the treatment of pterygium

Curative effect of pterygium resection and autologous limbal stem cell transplantation combined with amniotic membrane transplantation in the treatment of pterygium

Ten Years of Pediatric Ocular Chemical Burn Experience in a Tertiary Eye Care Center in Turkey.

To report 10 years of pediatric ocular chemical burn experience in a tertiary eye care center in Turkey. Thirty-three patients aged 18 years and younger who presented with ocular chemical burn between 2011 and 2021 were enrolled. Demographic data and clinical characteristics of patients were reviewed. Limbal stem cell deficiency (LSCD) stage was assessed according to LSCD working group's staging system. The initial and final best-corrected visual acuities were recorded. The mean age was 10.4±5.5 (0.25-18) years with an F/M ratio of 12/21. Eleven (33.3%) of the patients were injured with acid and 5 (15.1%) with alkaline. The most common causative agent was nail polish remover (n=7, 21.2%), followed by cologne (n=5, 15.1%) and hand sanitizer (n=4, 12.1%). The severity of burn was ≥grade 4 in 20 patients (60.6%). Chemical injury resulted in LSCD in 18 patients (54.5%). Surgery was performed (LSCD ≥Stage 2 B) in 13 patients (39.3%); limbal stem cell transplantation (LSCT) (n=11), staged amniotic membrane transplantation, and symblepharon release (n=2). Penetrating keratoplasty after LSCT was performed in three of 11 patients. The mean follow-up time was 31.9±28.6 months (6-102.33) after the surgery. In pediatric population, accurate diagnosis and management of ocular chemical burns are challenging. Although the severity of burn and consequently LSCD rate seems to be high in children, comparative studies in a larger population are still needed.

Management of limbal stem cell deficiency by amnion-assisted conjunctival epithelial redirection using vacuum-dried amniotic membrane and fibrin glue

PurposeTo study the outcome of a modified amnion-assisted conjunctival epithelial redirection (ACER) technique using vacuum-dried amnion (Omnigen) and fibrin glue for managing total limbal stem cell deficiency (LSCD).MethodA retrospective, interventional...

Mini-Review: Regenerating the Corneal Epithelium With Simple Limbal Epithelial Transplantation.

Simple limbal epithelial transplantation (SLET) is an ingenious, low cost and effective technique of limbal stem cell transplantation (LSCT) that is increasingly being undertaken in practice across the world. Since it was first described a decade ago, the technique has been performed in a variety of cases of limbal stem cell deficiency (LSCD) and has underwent several innovative modifications. Published literature on SLET has progressively increased over time and successful outcomes in various clinical scenarios have been reported. This concise review attempts to present a crisp account of SLET covering the indications and contraindications of performing the procedure; detailed account of pre-operative work up and preparation; surgical technique and its modifications; post-operative course, care and possible complications as well as published outcomes of surgery from across the world. Comparative analysis of various techniques of LSCT have been discussed and common concerns of surgeons practising or those who are planning to start practising SLET have been addressed. The authors hope that the pragmatic insights and pearls given at the end of the review will aid the surgeons in performing this technique to provide maximum benefit to patients suffering from the potentially blinding condition of LSCD.

Understanding Immune Responses to Surgical Transplant Procedures in Stevens Johnsons Syndrome Patients.

Stevens Johnsons syndrome (SJS) is a mucocutaneous disorder caused by an autoimmune response most commonly to medications. Unless it is properly managed in the acute setting, this entity can affect the ocular surface causing chronic cicatrizing conjunctivitis with limbal stem cell deficiency and lid anomalies which ultimately result in corneal opacities that may limit patients' visual acuity. When this stage is reached, some patients might need to undergo some form of corneal and/or limbal stem cell transplantation that exposes an already sensitized immune system to a new alloantigen. While the innate immunity plays a role in corneal graft survival, adaptive immune responses play a major part in corneal graft rejection and failure, namely through CD4+ T cell lymphocytes. Hence, the management of the immune response to surgical transplant procedures in SJS patients, involves a dual approach that modulates the inflammatory response to a new alloantigen in the context of an autoimmune sensitized patient. This review will explore and discuss current perspectives and future directions in the field of ocular immunology on how to manage SJS immune responses to ocular surgical procedures, reviewing systemic and local immunosuppressive therapies and protocols to adequately manage this debilitating condition.

Current perspectives of limbal-derived stem cells and its application in ocular surface regeneration and limbal stem cell transplantation.

Limbal stem cells are involved in replenishing and maintaining the epithelium of the cornea. Damage to the limbus due to chemical/physical injury, infections, or genetic disorders leads to limbal stem cell deficiency (LSCD) with partial or total vision loss. Presently, LSCD is treated by transplanting limbal stem cells from the healthy eye of the recipient, living‐related, or cadaveric donors. This review discusses limbal‐derived stem cells, the importance of extracellular matrix in stem cell niche maintenance, the historical perspective of treating LSCD, including related advantages and limitations, and our experience of limbal stem cell transplantation over the decades.

Limbal Stem Cells on Bacterial Nanocellulose Carriers for Ocular Surface Regeneration.

Limbal stem cells (LSCs) are already used in cell-based treatments for ocular surface disorders. Clinical translation of LSCs-based therapies critically depends on the successful delivery, survival, and retention of these therapeutic cells to the desired region. Such a major bottleneck could be overcome by using an appropriate carrier to provide anchoring sites and structural support to LSC culture and transplantation. Bacterial nanocellulose (BNC) is an appealing, yet unexplored, candidate for this application because of its biocompatibility, animal-free origin and mechanical stability. Here, BNC as a vehicle for human embryonic stem cells-derived LSC (hESC-LSC) are investigated. To enhance cell-biomaterial interactions, a plasma activation followed by a Collagen IV and Laminin coating of the BNC substrates is implemented. This surface functionalization with human extracellular matrix proteins greatly improved the attachment and survival of hESC-LSC without compromising the flexible, robust and semi-transparent nature of the BNC. The surface characteristics of the BNC substrates are described and a preliminary ex vivo test in simulated transplantation scenarios is provided. Importantly, it is shown that hESC-LSC retain their self-renewal and stemness characteristics up to 21 days on BNC substrates. These results open the door for future research on hESC-LSC/BNC constructs to treat severe ocular surface pathologies.

Therapeutic measures for sulfur mustard-induced ocular injury

The use of sulfur mustard (SM) in global terrorism is still a relevant threat to both civilian population and military personnel. Casualties exposed to SM may present mild, moderate or severe acute ocular lesions followed by a complete ocular resolution, chronic lesions or re-emerged ocular pathologies after a latent period.Current treatment for SM-induced ocular injury is based mainly on the clinical manifestation at the different stages of the injury and includes pharmaceutical and surgical interventions. These therapeutic measures are beneficial but not sufficient, and the ocular injury remains a continuous challenge for medical professionals.This review focuses on treatment experience carried out in humans and studied in animal models, for both SM-induced ocular acute injury and late pathology. In general, therapeutic measures are based on clinical features of the ocular injury or on the involvement of specific factors during the ocular injury that point out towards potential treatments. Anti-inflammatory treatments and limbal stem cell transplantation techniques were developed based on the clinical manifestation of the ocular injury. Optional therapies for impaired corneal innervation and endothelium are suggested for future research. Additionally, studies on potential treatments with anti-matrix metalloproteinase (MMP), anti-vascular endothelial growth factor (VEGF) and anti-IL-6 agents are discussed.Consequently, future studies may reveal the potential of additional pharmacological and biological treatments or advanced cellular and molecular biology methods to serve as novel therapeutic measures and techniques for this complicated ocular injury.

Outcomes of surgical interventions for the treatment of limbal stem cell deficiency.

Background & objectives:In the current scenario, with availability of different surgical procedures for limbal stem cell deficiency (LSCD), there exists no common consensus as to the standardization of the management protocol for the same. In addition, there also exists diversity in the views about the clinical diagnosis, ancillary investigations and clinical parameters. The objective of the present study was to evaluate the reported outcomes of surgical interventions for the management of LSCD.Methods:A systematic review of published literature on limbal stem cell transplantation (LSCT) was performed using Ovid Medline, Embase and PubMed for a duration of 2009 to 2019. Original studies including prospective, retrospective case series and randomized controlled trials, articles in English language, articles with access to full text and studies with more than or at least 10 patients were included in this review. Data related to clinical and visual outcomes were evaluated, and pool estimates of different surgeries were calculated using random-effects model and individually using Pearson’s Chi-square test.Results:A total of 1133 abstracts were evaluated. Finally, 17 studies were included for the analysis. Among these 17 studies, direct limbal lenticule transplantation was performed in five studies, of which autologous tissue from the fellow eye [conjunctival limbal autograft (CLAU)], allograft from a cadaver/live donor [keratolimbal allograft (KLAL)/conjunctival limbal allograft (CLAL)] and combination of CLAU plus KLAL were done in one, three and one studies, respectively. The ex vivo expanded cultivated limbal epithelial transplantation (CLET) was reported in six studies and simple limbal epithelial transplantation (SLET) in four studies. Two were comparative studies comparing CLET and CLAL (living-related CLAL) with cadaveric KLAL, respectively. Outcome analysis of the included studies showed significant heterogeneity. Calculated pool rate for various types of surgeries was calculated. The pool estimate for CLAL was 67.56 per cent [95% confidence interval (CI), 41.75-93.36; I2=83.5%, P=0.002]. For KLAL, this value was 63.65 per cent (95% CI, 31.38-95.91; I2=92.4%, P=0.000). Pool estimate for CLET was 78.90 per cent (95% CI, 70.51-87.28; I2=73.6%, P=0.001). Corresponding values for SLET were 79.08 per cent (95% CI, 74.10-84.07; I2=0.0%, P=0.619). CLAU and combination of CLAU plus KLAL were done in one study each; hence, statistical analysis could not be done. The functional outcome in terms of gain in visual acuity post-operatively was better in KLAL (P<0.005) and SLET group as compared to CLET group.Interpretation & conclusions:The present analysis suggests that though the anatomical success rates were almost identical between SLET, CLET, CLAL, and KLAL procedures, the functional success rates were better following KLAL and SLET procedures as compared to CLET. Decision for LSCT for cases of ocular burns based on either clinical judgement of the surgeon or individual diagnosis remains a suitable option.

Clinical outcomes and safety of Diphoterine® irrigation for chemical eye injury: A single-centre experience in the United Kingdom.

Purpose:Diphoterine® is an amphoteric irrigating solution armed with rapid pH-neutralising action. It serves as an effective first-aid treatment for managing chemical burns, including chemical eye injury (CEI). However, its use is not widely adopted in current clinical practice, primarily attributed to limited clinical evidence. This study aims to highlight the experience in using Diphoterine for managing CEI in a UK tertiary referral centre.Methods:This retrospective case series included all patients who presented with CEI and treated with Diphoterine at the James Cook University Hospital, UK, between April 2018 and February 2020.Results:Seven patients (10 eyes) were included; the mean age was 28.2 ± 17.0 years (ranged, 3–70 years) and 85.7% were male. All patients presented with an alkaline injury with a mean presenting pH of 8.7 ± 0.7 and a median (±interquartile range [IQR]) corrected-distance visual acuity (CDVA) of 0.10 ± 0.28 logMAR. Based on Roper-Hall classification, 90% and 10% of the eyes were of grade-I and -IV CEI, respectively. All eyes received normal saline/water as the first irrigation fluid and Diphoterine as second irrigation fluid. The mean pH improved slightly after first irrigation (8.4 ± 0.7; p = 0.13) and significantly after second irrigation (7.6 ± 0.4; p = 0.001). The volume of irrigation used was significantly less for Diphoterine (520 ± 193 mL) than for normal saline/water (2700 ± 2451 mL; p = 0.016). At final follow-up (median = 5 days), the median CDVA remained stable at 0.10 ± 0.28 logMAR (p = 0.60). One patient developed near-total limbal stem cell deficiency as a complication of grade-IV injury and was awaiting limbal stem cell transplantation at last follow-up.Conclusion:This study represents the first case series in the United Kingdom, reporting the use of Diphoterine in managing CEI. The rapid pH-neutralising action of Diphoterine, with less volume required, makes it an ideal initial treatment for efficiently managing adult and paediatric patients with CEI in clinics.

Tectonic Keratoplasty in Patients with Non-traumatic, Non-infectious Corneal Perforations

Introduction:The study aims to report clinical results of tectonic keratoplasty for non-traumatic, non-infectious corneal perforations.Materials and Methods:The medical records of 12 patients who underwent tectonic penetrating keratoplasty between October 2014 and August 2018 at Ege University Ophthalmology Department were retrospectively reviewed.Results:The mean age of the patients was 52.92±30.34 (range, 2-82) years. The causes of corneal perforation were dry eye (neurotrophic keratopathy (n=4), limbal stem cell deficiency (n=2), exposure keratopathy (n=2) and graft versus host disease (n=1)) in 9 patients. In the remaining 3 patients, the etiology of perforation was not determined. The mean Visual Acuity (VA) was 2.98±0.39 (range, 1.8-3.1) LogMAR before the surgery. Despite conservative treatment, tectonic penetrating keratoplasty had to be performed in all patients in order to manage the perforation. Mean time in between initial examination and surgery was 10.75±12.04 (1-41) days. In 2 patients, allogenic limbal stem cell transplantation; in one patient, lateral tarsorrhaphy and in one patient symblepharon release with amniotic membrane transplantation were performed additional to tectonic keratoplasty. Mean follow-up time was 57.88±55.47 (4-141) weeks. Grafts were clear in 6 eyes and opaque in 5 eyes. The main causes of graft failure among opaque grafts were ocular surface disease (3), allograft rejection (1) and glaucoma-related endothelial failure (1). Phthisis bulbi was detected in one patient with congenital glaucoma due to vitreous loss at the time of perforation. The mean final VA in patients who had clear grafts was 1.83±1.03 (range, 0.8-3.1) LogMAR.Conclusion:To prevent serious complications in non-traumatic, non-infectious corneal perforations, providing anatomic integrity immediately is a must. If conservative treatment is inadequate or the perforation area is extensive, tectonic penetrating keratoplasty is indicated. Besides, it is important to manage the etiological risk factors in order to obtain successful clinical follow up.

Immunocytochemistry of the ocular surface after different techniques of limbal stem cell transplantation for chronic chemical burns

AimTo compare the immunocytochemistry (ICC) on impression cytology of corneal surface epithelium after simple limbal epithelial transplantation (SLET) and conjunctival-limbal autograft (CLAU).MethodsA prospective study of 20 patients above 1 year...

Research progress on limbal stem cell transplantation

Limbal Stem Cell Deficiency (LSCD) is an ocular surface disease caused by the decrease of the quantity and dysfunction of limbal stem cell, which is characterized by conjunctivalization and other signs of epithelial dysfunction. For sever LSCD, surgery is the main treatment way. Recently, plenty of researches published the outcomes of different operation methods. This article summarized five major operations, including conjunctival limbal autograft (CLAU), simple limbal epithelial transplantation (SLET), limbal allograft, cultivated limbal stem cell transplantation (CLET) and cultivated oral mucosal epithelial transplantation (COMET). (Chin J Ophthalmol, 2020, 56:956-960).

Experimental study of synthetic polymeric materials as a basis for developing advanced carrier matrices for cultivating limbal stem cells

Objective: to conduct an experimental study on the properties of three different types of synthetic polyester matrices, to carry out their comparative assessment, and to identify the optimal carrier for the cultivation and transplantation of limbal stem cells while eliminating limbal insufficiency. Materials and methods. Transparency, mechanical properties (strength, relative elongation at break, and elastic modulus), biocompatibility with corneal cell cultures were assessed, and duration of matrix biodegradation in vivo were studied. Results. In the course of our study, the optical and mechanical properties of matrices, made of polylactide-glycolide (PLG), polylactide-caprolactone (PLC) and poly-E-caprolactone (PCL), were studied. It has been experimentally shown that limbal stem cells of humans and rabbits, as well as human corneal epithelial cells, adhered to the surface of all types of the studied matrices. During the cultivation process, they retained the typical structure of the actin cytoskeleton, along with the ability to proliferate and migrate. Differences in the interaction of different cell cultures with different types of carriers were revealed. The biodegradation time of 5 μm thick PLC matrices was about 30 days. Conclusion. Our results obtained implied the possibility of using 5 µm thick PLC matrices as a carrier for cultured limbal stem cells.

Opening the Soul Window Manually: Limbal Tissue Scaffolds with Electrospun Polycaprolactone/Gelatin Nanocomposites.

Restricted by the difficulty in fabricating scaffolds suitable for cell proliferation, the use of ex vivo expanded limbal stem cell (LSC) for LSC transplantation, an effective treatment method for patients with limb stem cell deficiency (LSCD), is hard to be widely used in clinical practice. To tackle these challenges, a novel electrospun polycaprolactone (PCL)/gelatin nanocomposite is proposed to make 3D scaffolds for limbal niche cells (LNC) proliferation in vitro, which is a milestone in the treatment of diseases such as LSCD. PCL and gelatin in different weight ratios are dissolved in a mixed solvent, and then electrospinning and cross-linking are performed to prepare a scaffold for cell proliferation. The characterizations of the nanocomposites indicate that the gelatin content has a significant effect on its micro-morphology, thermal properties, crystallinity, degradation temperature, hydrophilicity, and mechanical properties. P8G2-C (PCL: gelatin = 80: 20, cross-linked), with smooth fibers and homogeneous pores, has better hydrophilicity, mechanical properties, and flexibility, so it can support LNC as cell proliferation assays revealed. This detailed investigation presented here demonstrates the feasibility of using PCL/gelatin nanocomposites electrospun fiber membranes as a limbus tissue engineering scaffold, which undoubtedly provide a new perspective for the development of tissue engineering field.

Herpetic keratitis mimicking chronic limbal stem cell failure

To describe four cases of herpetic keratitis after cultivated limbal stem-cell transplantation (CLET). Four patients affected by limbal stem cell deficiency (LSCD) caused by alkali burns received CLET. During regular follow-up, epithelial defects were detected and corneal scraping was performed to identify active viral keratitis. Herpetic epithelial keratitis was successfully diagnosed by corneal scraping and polymerase chain reaction of HSV-1 DNA in all four patients affected by epithelial defects. The defects resolved after appropriate therapy with topical and/or systemic antiviral drugs. Epithelial defects due to herpetic keratitis after cultivated limbal stem-cell transplantation may mimic chronic stem-cell deficiency. A low-threshold for corneal scraping can yield rapid identification of herpetic viral DNA allowing for appropriate treatment.

Efficacy of amniotic membrane graft in ocular surface disorders

Amniotic membrane transplantation is the newest approach to limbal stem cell transplantation for the reconstruction of ocular surface disorders. Amniotic membrane grafting helps in promoting epithelialisation, decreasing inflammation and suppressing fibrosis. To evaluate the use of amniotic membrane graft in patients coming to Dr B.R. Ambedkar Medical college OPD and IPD with various ocular surface disorders.The prospective interventional study was conducted over a period of 18 months from June 2017 to November 2018 at DR. B. R. Ambedkar medical college and hospital, Bengaluru.A total of 46 eyes of 46 patients were taken into the study. Consecutive patients with ocular surface disorders including primary pterygia and chemical injury underwent amniotic membrane transplantation and were followed for 6 months. In our study, 46 patients were enrolled including 26 males and 20 females with mean age of 43.3 +/- 12.97 years. Of these, there were 40 patients with Pterygium (87%), 6 patient’s had chemical burn (13%). Out of 40 cases with primary pterygium, 35 cases (87.5%) showed no recurrences at the 6 month of follow up, 5 cases (12.5%) showed superficial vascularisation and re-growth upto 2mm crossing the limbal margin. The recurrence was early in two cases (5%) and late in three cases (7.5%). Out of 6 cases with chemical injury, 4 patients (66.6%) had successful outcome.Amniotic membrane transplantation is a safe and effective surgical technique for ocular surface disorders.

A comparative study of graft stability, complication profiles and patient comfort among sutureless glue-free and sutured conjunctivo limbal autograft in pterygium surgery of Western Rajasthan

Pterygium is a triangular encroachment of bulbar conjunctiva on to the cornea known for high recurrence rate. Various adjunctive measures were used to reduce the recurrence rate. Nowadays thoughutureless and glue-free conjunctival autograft has been encouraged for treating primary pterygium yet sutured conjunctival autograft is also extensively performed. To assess and compare graft stability, complication profiles and patient comfort in sutureless glue-free and sutured conjunctivo limbal autograft in pterygium surgery and to assess postoperative improvement in parameters associated with visual defects due to pterygium.Sutured conjunctival autograft were done in 25 patients (group A), and sutureless and glue-free conjunctival autograft was done in 25 patients (group B). Postoperative discomfort was assessed for 90 days during which graft related complications and recurrence if any were noted. Pre and postoperative parameters associated with visual defects due to pterygium were also compared. Total number of patients who developed postoperative complications was 22(88%) in Group A and 15(60%) patients in Group B. Number of patients with postoperative discomfort was significantly less in group B after 1 week and almost nil on 30 day. In Group A one patient graft unstability and in Group B two patients showed graft unstability.Sutureless glue free auto conjunctivo limbal stem cell transplantation showed significantly better patients comfort and decreases suture related complications.

Management Strategies of Ocular Chemical Burns: Current Perspectives.

Ocular chemical burns are absolute ophthalmic emergencies and require immediate management to minimize devastating sequelae. Management of alkali and acid burns is started at the scene of the accident by copious irrigation. Treatment is directed at improving epithelial integrity and stromal stability, reduction of undue inflammation, and prevention or timely management of complications. To ascertain the best possible outcome, numerous biological medications and surgical interventions have been merged into conventional therapeutic regimens. These include autologous and umbilical cord serum preparations, platelet-rich plasma, amniotic membrane transplantation, limbal stem-cell transplantation, and anti-angiogenic agents.

Wound healing following amniotic membrane, limbal stem cell and corneal transplantation

Knowledge of wound healing processes involved in amniotic membrane, limbal stem cell and corneal transplantation enables an assessment of clinical findings and a targeted treatment. The amniotic membrane serves as abasal membrane substrate or temporary transplant in corneal epithelial wound healing. It has an anti-inflammatory effect, supports corneal wound healing and counteracts scar formation. Amniotic membranes are integrated intraepithelially, subepithelially, or intrastromally in the course of healing. Limbal epithelial stem cells express multiple genes necessary for corneal wound healing. The rho-associated, coiled-coil containing protein kinase (ROCK) inhibitor Y‑27632 can improve the proliferation of limbal epithelial cells and therefore represents anew therapeutic option for limbal stem cell deficiency. Wound healing following penetrating keratoplasty involves fibroblasts, typeIII and IV collagens, proteoglycans, and chondroitin-6-sulfate. Acertain inflammatory reaction seems to be necessary for final corneal wound closure.